Yet another run at reduce (collect)

[Brian Goetz]

> And further, I think this is a net positive win in terms of
> understandability. For example:
>
>     reduce(intoList()) => collect(intoList())
>
> The name provides a pleasant and appropriate clue that it is
> something often applicable to Collections.
>
> Try it out on other examples.

   collect(groupBy(...))
   collect(partition(...))
   collect(mappedTo / toMap))